Creating a Sliding Window View Over a Data Range

Creating a sliding window view over a data range can be achieved using custom iterators or by leveraging existing libraries. C++20 does not provide a built-in sliding window view, but we can create one using a custom view.

Example: Sliding Window View

Here's a basic implementation of a sliding window view:

1#include <iostream>
2#include <ranges>
3#include <vector>
4
5template <typename T>
6class SlidingWindowView
7  : public std::ranges::view_base {
8 public:
9  SlidingWindowView(
10    std::vector<T>& data,
11    std::size_t window_size
12  ) : data_(data), window_size_(window_size) {}
13
14  auto begin() const {
15    return Iterator{data_, 0, window_size_};
16  }
17
18  auto end() const {
19    return Iterator{
20      data_,
21      data_.size() - window_size_ + 1,
22      window_size_
23    };
24  }
25
26 private:
27  std::vector<T>& data_;
28  std::size_t window_size_;
29
Iterator Class|Show
30  class Iterator {/*...*/};
61};
62
63int main() {
64  std::vector<int> Numbers{
65    1, 2, 3, 4, 5, 6, 7, 8, 9};
66
67  SlidingWindowView<int> view(Numbers, 3);
68
69  for (auto window : view) {
70    for (int Num : window) {
71      std::cout << Num << " ";
72    }
73    std::cout << "\n";
74  }
75}

11 2 3 
22 3 4 
33 4 5 
44 5 6 
55 6 7 
66 7 8 
77 8 9

Explanation

• SlidingWindowView: A custom view class that takes a data vector and window size.
• begin() and end(): Define the range of the sliding window.
• Range-Based For Loop: Iterates through the data, printing each sliding window.

Using the Range-V3 Library

The Range-V3 library offers a sliding view which simplifies the creation of sliding windows:

1#include <iostream>
2#include <range/v3/view/sliding.hpp>
3#include <vector>
4
5int main() {
6  std::vector<int> Numbers{1, 2, 3, 4, 5, 6, 7, 8, 9};
7
8  auto view = Numbers | ranges::views::sliding(3);
9
10  for (const auto& window : view) {
11    for (int Num : window) {
12      std::cout << Num << " ";
13    }
14    std::cout << "\n";
15  }
16}

11 2 3
22 3 4
33 4 5
44 5 6
55 6 7
66 7 8
77 8 9

Explanation

• Range-V3: A library that extends C++'s range functionality.
• views::sliding: Provides a built-in sliding view, simplifying window creation.

Benefits of Sliding Window Views

• Data Analysis: Useful in scenarios like moving averages, trend analysis, and more.
• Modularity: Easily integrates into existing data processing pipelines.
• Efficiency: Processes data in chunks, optimizing performance for large datasets.

Sliding window views enable powerful data processing techniques, allowing for efficient analysis and manipulation of data in contiguous subranges.